diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 19fbc842..5c4c315b 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -76,7 +76,13 @@ jobs:
     name: Semantic Release
     runs-on: ubuntu-latest
     needs: pre-release-tests
-    if: "!startsWith(github.event.head_commit.message, 'chore(release):')"
+    # Prevent duplicate execution when semantic-release creates chore(release) commit
+    # IMPORTANT: If .releaserc.cjs message format changes, update this condition
+    if: |
+      !(
+        github.event.head_commit.author.name == 'github-actions[bot]' &&
+        startsWith(github.event.head_commit.message, 'chore(release):')
+      )
 
     outputs:
       new_release_published: ${{ steps.semantic.outputs.new_release_published }}
@@ -142,10 +148,18 @@ jobs:
     name: Merge to main
     needs: semantic-release
     runs-on: ubuntu-latest
+    # Execute merge when:
+    # 1. semantic-release created a new release, OR
+    # 2. This is a re-triggered run from semantic-release's chore(release) commit
     if: |
       always() &&
-      (needs.semantic-release.outputs.new_release_published == 'true' ||
-       startsWith(github.event.head_commit.message, 'chore(release):'))
+      (
+        needs.semantic-release.outputs.new_release_published == 'true' ||
+        (
+          github.event.head_commit.author.name == 'github-actions[bot]' &&
+          startsWith(github.event.head_commit.message, 'chore(release):')
+        )
+      )
 
     steps:
       - name: Checkout
diff --git a/.releaserc.cjs b/.releaserc.cjs
index c040cbd4..ce8af698 100644
--- a/.releaserc.cjs
+++ b/.releaserc.cjs
@@ -54,6 +54,10 @@ module.exports = {
           'CHANGELOG.md',
           'UnityMCPServer/Packages/unity-mcp-server/package.json'
         ],
+        // IMPORTANT: Changing this message format requires updating .github/workflows/release.yml
+        // The workflow uses this format to detect and skip duplicate executions:
+        // - semantic-release job: skips when message starts with 'chore(release):'
+        // - merge-to-main job: executes when message starts with 'chore(release):'
         message: 'chore(release): ${nextRelease.version}\n\n${nextRelease.notes}'
       }
     ],
diff --git a/CHANGELOG.md b/CHANGELOG.md
index f69bed88..6835c3bd 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,10 @@
+## [2.40.1](https://github.com/akiojin/unity-mcp-server/compare/v2.40.0...v2.40.1) (2025-11-18)
+
+
+### Bug Fixes
+
+* **ci:** improve release workflow duplicate execution prevention ([241cf79](https://github.com/akiojin/unity-mcp-server/commit/241cf797c4bb8b2e88a034d09c6ab2b5eca012c1))
+
 ## [2.40.0](https://github.com/akiojin/unity-mcp-server/compare/v2.39.2...v2.40.0) (2025-11-18)
 
 
diff --git a/UnityMCPServer/Packages/unity-mcp-server/package.json b/UnityMCPServer/Packages/unity-mcp-server/package.json
index 6e488af1..0afa0335 100644
--- a/UnityMCPServer/Packages/unity-mcp-server/package.json
+++ b/UnityMCPServer/Packages/unity-mcp-server/package.json
@@ -1,7 +1,7 @@
 {
   "name": "com.akiojin.unity-mcp-server",
   "displayName": "Unity MCP Server",
-  "version": "2.40.0",
+  "version": "2.40.1",
   "unity": "6000.0",
   "description": "Unity MCP Server bridge and tooling for AI-assisted development (screenshots, video capture, scene analysis, input automation).",
   "keywords": [
diff --git a/mcp-server/package.json b/mcp-server/package.json
index 7c65a976..598b086f 100644
--- a/mcp-server/package.json
+++ b/mcp-server/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@akiojin/unity-mcp-server",
-  "version": "2.40.0",
+  "version": "2.40.1",
   "description": "MCP server and Unity Editor bridge — enables AI assistants to control Unity for AI-assisted workflows",
   "type": "module",
   "main": "src/core/server.js",